#include "ringbuffer.h"

/**
 * @file
 * Implementation of ring buffer functions.
 */

void ring_buffer_init(ring_buffer_t *buffer) {
	buffer->tail_index = 0;
	buffer->head_index = 0;
}

void ring_buffer_queue(ring_buffer_t *buffer, char data) {
	/* Is buffer full? */
	if(ring_buffer_is_full(buffer)) {
		/* Is going to overwrite the oldest byte */
		/* Increase tail index */
		buffer->tail_index = ((buffer->tail_index + 1) & RING_BUFFER_MASK);
	}

	/* Place data in buffer */
	buffer->buffer[buffer->head_index] = data;
	buffer->head_index = ((buffer->head_index + 1) & RING_BUFFER_MASK);
}

void ring_buffer_queue_arr(ring_buffer_t *buffer, const char *data, ring_buffer_size_t size) {
	/* Add bytes; one by one */
	ring_buffer_size_t i;
	for(i = 0; i < size; i++) {
		ring_buffer_queue(buffer, data[i]);
	}
}

uint8_t ring_buffer_dequeue(ring_buffer_t *buffer, char *data) {
	if(ring_buffer_is_empty(buffer)) {
		/* No items */
		return 0;
	}
	
	*data = buffer->buffer[buffer->tail_index];
	buffer->tail_index = ((buffer->tail_index + 1) & RING_BUFFER_MASK);
	return 1;
}

ring_buffer_size_t ring_buffer_dequeue_arr(ring_buffer_t *buffer, char *data, ring_buffer_size_t len) {
	if(ring_buffer_is_empty(buffer)) {
		/* No items */
		return 0;
	}

	char *data_ptr = data;
	ring_buffer_size_t cnt = 0;
	while((cnt < len) && ring_buffer_dequeue(buffer, data_ptr)) {
		cnt++;
		data_ptr++;
	}
	return cnt;
}

uint8_t ring_buffer_peek(ring_buffer_t *buffer, char *data, ring_buffer_size_t index) {
	if(index >= ring_buffer_num_items(buffer)) {
		/* No items at index */
		return 0;
	}
	
	/* Add index to pointer */
	ring_buffer_size_t data_index = ((buffer->tail_index + index) & RING_BUFFER_MASK);
	*data = buffer->buffer[data_index];
	return 1;
}

extern inline uint8_t ring_buffer_is_empty(ring_buffer_t *buffer);
extern inline uint8_t ring_buffer_is_full(ring_buffer_t *buffer);
extern inline ring_buffer_size_t ring_buffer_num_items(ring_buffer_t *buffer);



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